Inspection and Verification

Certain axle noise or vibration symptoms are also common to the engine,
transmission, wheel
bearings, tires, and other parts of the vehicle. For this reason, be sure that
the cause of the trouble is
in the axle before disassembling, adjusting or repairing the axle.
Certain driveshaft vibration symptoms are common to the front engine accessory
drive (FEAD), the
engine, transmission or tires. Be sure the cause of the concern is the
driveshaft before repairing or
installing a new driveshaft.
Certain symptoms may be caused by Traction-Lok differentials (4026). Check the
vehicle certification
label and axle identification tag to determine the type of differential.

Noise Acceptability

NOTE: A gear-driven unit will produce a certain amount of noise. Some
noise is acceptable and
audible at certain speeds or under various driving conditions such as a newly
paved blacktop road.

Slight noise is not detrimental to the operation of the axle and is considered
normal.

With the Traction-Lok differential axle, slight chatter noise on slow turns
after extended highway
driving is considered acceptable and has no detrimental effect on the locking
axle function.

Universal Joint (U-Joint) Inspection

Place the vehicle on a frame hoist and rotate the driveshaft (4602) by hand.
Check for rough operation
or seized U-joints. Install a new U-joint if it shows signs of seizure,
excessive wear, or incorrect
seating.

Analysis of Leakage

Clean up the leaking area enough to identify the exact source. An axle leak
can be caused by the
following.

Axle lubricant level is too high.

Worn or damaged axle shaft seals or differential seals.

Differential housing is cracked.

Flange yoke seat is worn or damaged.

Pinion flange is scored or damaged.

Axle cover is not sealed.

Vent is plugged.

Repair the axle as necessary. Make sure the axle lubricant is at the correct
level. Refer to
Specifications in this section.

Axle Vent

NOTE: If a plugged vent cannot be cleared, install a new one.

A plugged vent will cause excessive seal lip wear due to internal pressure
buildup. If a leak occurs,
check the vent. Make sure the vent hose is not kinked. Remove the hose from the
vent nipple and
clear the hose of any foreign material. While the hose is removed, pass a length
of mechanics wire in
and out of the vent to clean it. Connect the hose when done.

Flange Yoke Seal

Leaks at the axle drive pinion seal originate for the following reasons:

Seal was not correctly installed.

Poor quality seal journal surface.

Any damage to the seal bore (dings, dents, gouges, or other imperfections)
will distort the seal casing
and allow leakage past the outer edge of the axle drive pinion seal.

The axle drive pinion seal can be torn, cut, or gouged if it is not installed
carefully. The spring that
holds the axle drive pinion seal against the pinion flange may be knocked out
and allow leakage past
the lip.

The rubber lips can occasionally become hard (like plastic) with cracks at the
oil lip contact point. The
contact point on the pinion flange may blacken, indicating excessive heat.
Marks, nicks, gouges, or
rough surface texture on the seal journal of the pinion flange will also cause
leaks.

When a seal leak occurs, install a new seal and check the vent and the vent hose
to make sure they
are clean and free of foreign material.

Axle Shaft Seals

Axle shaft oil seals are susceptible to the same kinds of damage as axle
drive pinion seals if incorrectly
installed. The seal bore must be clean and the lip handled carefully to avoid
cutting or tearing it. The
axle shaft journal surface must be free of nicks, gouges, and rough surface
texture.

Analysis of Vibration

WARNING: A vehicle equipped with a Traction-Lok differential will
always have both
wheels driving. If only one wheel is raised off the floor and the rear axle is
driven by the engine,
the wheel on the floor could drive the vehicle off the stand or jack. Be sure
both rear wheels are
off the floor.

Few vibration conditions are caused by the rear axle. On a vibration concern,
follow the diagnosis
procedure in Section unless there is a good reason to suspect the axle.

Tires

WARNING: Do not balance the wheels and tires while they are mounted on
the vehicle.

Vibration is a concern with modern, high-mileage tires if they are not "true"
both radially and laterally.

They are more susceptible to vibration around the limits of radial and lateral
runout of the tire and
wheel assembly. They also require more accurate balancing. Wheel and tire runout
checks, truing and
balancing are normally done before axle inspection.

Driveline Angle

Driveline angularity is the angular relationship between the engine
crankshaft (6303), the driveshaft,
and the rear axle pinion. Factors determining driveline angularity include ride
height, rear spring, and
engine mounts.

Exceptions To Normal Schedule
General Maintenance Information
NOTE: This is a generic maintenance schedule for all Ford, Lincoln and
Mercury vehicles. There may
be items listed that do not apply to all vehicles.
The Normal Schedule applies to operation of the vehicle under typical, every ...